Various structures have been heretofore designed to enable a flexible cover to be lengthwise extended over a load within a load bed projecting above the side walls of the load bed.
The prior art structure most pertinent to the instant invention is disclosed in my prior U.S. Pat. No. 3,515,428. In addition, structures for accomplishing the same general purpose are disclosed in U.S. Pat. Nos. 3,041,104, 3,168,345 and 3,179,464.